deps: update dependency com.google.cloud:google-cloud-spanner-bom to v6.81.2 (#6865)

* deps: update dependency com.google.cloud:google-cloud-spanner-bom to v6.81.1

* deps:update dependency com.google.cloud:google-cloud-spanner-bom to v6.81.2

---------

Co-authored-by: Jin Seop Kim <[email protected]>

Author: renovate-bot

google-cloud-bom/pom.xml

@@ -238,7 +238,7 @@
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-spanner-bom</artifactId>
-        <version>6.80.1</version>
+        <version>6.81.2</version>
         <type>pom</type>
         <scope>import</scope>
       </dependency>